Download or read book High Resolution Molecular Characterization of Photochemical and Microbial Transformation of Dissolved Organic Matter in Temperate Streams of Different Watershed Land Use written by Xiaping Li and published by . This book was released on 2014 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the present study was to provide better understanding of the effects of watershed land use on molecular composition of streamwater DOM and molecular transformations associated with photochemical and microbial processing of DOM. We compared DOM from headwater streams draining forest-dominated watersheds (FW) and pasture-dominated watersheds (PW) in the lower Chesapeake Bay region (Virginia, USA). Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry analysis was conducted on streamwater DOM prior to and after laboratory incubations: 1) bacteria-only incubations; 2) light-only incubations; and 3) combined light+bacterial incubations. Results showed that DOM in FW streams and PW streams differed in molecular characteristics--the former was characterized by greater structural complexity and aromaticity, higher proportions of condensed aromatic molecules and black carbon-like components, while the latter was higher in the proportions of lipid-like components, protein-like components and aliphatic compounds. Relative to DOM from FW streams, DOM from PW streams was more reactive to bacterial transformation. Protein-like components, lipid-like components and unsaturated hydrocarbon-like components are primarily responsible for the changes associated with bacterial transformation of DOM. However, similar behavior was also observed for DOM in FW streams and PW streams under the influence of bacterial and photochemical processes. Bacterial transformation reduced the proportions of lipid-like components but increased the proportions of lignin-like components and carboxyl-rich alicyclic molecule-like components, indicating that lipid-like components was a bioreactive class while lignin-like components and carboxyl-rich alicyclic were resistant to bacterial processing. Photochemical processes, alone or combined with microbial alterations, increased the proportions of protein-like components, which may be due to the light stimulation of autochthonous production of protein-like components, and increased the relative abundance of carboxyl-rich alicyclic molecule-like components, which indicates the refractory nature of these molecules. Photochemical processes also significantly reduced the amount of dissolved black carbon-like components, which suggests dissolved black carbon was a photoreactive class, countering the conventional view that black carbon was an inter group in carbon cycle. Collectively, these findings suggest that human land use in upstream watersheds may lead to alterations to the molecular composition of streamwater DOM as well as to its behavior to photochemical and microbial processing.

Download or read book Molecular Characterization and Photochemical Transformation of Dissolved Organic Matter from Land to Ocean written by Hongmei Chen and published by . This book was released on 2014 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Linking Optical and Chemical Properties of Dissolved Organic Matter in Natural Waters written by Christopher L. Osburn and published by Frontiers Media SA. This book was released on 2017-01-17 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: A substantial increase in the number of studies using the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) as a proxy for its chemical properties in estuaries and the coastal and open ocean has occurred during the last decade. We are making progress on finding the actual chemical compounds or phenomena responsible for DOM’s optical properties. Ultrahigh resolution mass spectrometry, in particular, has made important progress in making the key connections between optics and chemistry. But serious questions remain and the last major special issue on DOM optics and chemistry occurred nearly 10 years ago. Controversies remain from the non-specific optical properties of DOM that are not linked to discrete sources, and sometimes provide conflicting information. The use of optics, which is relatively easier to employ in synoptic and high resolution sampling to determine chemistry, is a critical connection to make and can lead to major advances in our understanding of organic matter cycling in all aquatic ecosystems. The contentions and controversies raised by our poor understanding of the linkages between optics and chemistry of DOM are bottlenecks that need to be addressed and overcome.

Download or read book Watershed Export of Dissolved Organic Matter in Response to Anthropogenic and Hydroclimatic Drivers in Subtropical Streams and Rivers written by Shuo Chen and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is an assemblage of heterogeneous organic compounds that play important roles in terrestrial and aquatic ecosystems. In this dissertation, I investigated changes in the amount, source, composition, lability, and ecological functions of stream water DOM in response to agricultural land use, hydrological events, and downstream transport and transformation in the southeastern United States. The dissertation includes three stand-alone studies presented in Chapters 2, 3 and 4, respectively. In Chapter 2, I evaluated the effects of hurricane-induced storm events on the quantity and quality of DOM exported from ten watersheds of various physical and land-use characteristics within five Gulf and South Atlantic states. We found that large storms can significantly enhance the concentrations and yields of terrestrially-derived dissolved organic carbon (DOC) and nutrients in streams and rivers but decrease the percentage bioreactive DOC. This study demonstrates that extreme weather and climate events can lead to rapid, ecosystem-level disturbances that significantly shift energy and nutrient availability within drainage networks. The objective of Chapter 3 was to quantify the relative importance of agricultural land use and natural hydroclimatic drivers in affecting the quality and quantity of DOM in a group of 15 streams draining watersheds of a gradient of agricultural land use. The partial least square path modeling (PLS-PM) identified that agricultural land use increased stream water DOM quantity primarily through increasing allochthonous carbon sources. This study demonstrates that structural equation modeling is a powerful tool that should be more widely adopted to distinguish among multiple drivers and mechanisms regulating freshwater biogeochemistry. Chapter 4 investigated the longitudinal transformations of DOM in relation to ecosystem metabolism along a fluvial section including 3rd order, 7th and 8th order streams. From upstream to downstream, DOC concentrations and the relative contributions of freshly-produced DOM increased. The gross primary productivity was positively correlated with the contributions of autochthonous DOM, yet the ecosystem respiration did not vary with the quantity or quality of DOM. This study highlights the complexity of DOM transformations in relation to stream metabolism along the river continuum. Collectively, the three independent but connected studies reveal the complexity and sensitivity of inland water DOM in response to hydroclimatic and anthropogenic drivers. The findings provide new insights into potential shifts in energy and substrates exported across the terrestrial-aquatic boundary due to human activities and climate change and how these shifts can alter water quality and fluvial biogeochemical functions.

Download or read book Microbial and Photochemical Cycling of Dissolved Organic Matter in Boreal Headwater Streams written by Doreen Franke and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a key global energy source and carbon reservoir that links terrestrial and aquatic biogeochemical cycling. Allochthonous organic matter is abundant in boreal headwater streams, and environmental changes such as variation in nutrient availability and changes to watershed landscape composition have great potential for altering the DOM source, its composition and cycling. This dissertation focuses on two of the main drivers of aquatic carbon and nutrient cycling: the photochemical and the microbial processing of DOM in boreal headwater streams; specifically (i) how the photochemical lability of DOM varies between reaches within headwater streams, among headwater streams and an associated large river reach, (ii) how stream biofilm mineralization may be regulated by watershed organic matter source and composition, increased labile carbon, nitrogen, and phosphorus availability, and (iii) whether algal carbon sources are important to supporting stream biofilms and if such sources influence the use of allochthonous DOM in nutrient-enriched streams. The results suggest changes in landscape and nutrient availability have the potential to alter the photochemical and biogeochemical cycling of DOM. DOM photolability was increased upstream relative to downstream and the river DOM. This may be due to differences in DOM source and composition, and suggests losses in photolabile DOM downstream and in the lower reaches of the watershed. The phototransformation of DOM into low molecular weight compounds and nutrients such as ammonium is likely relevant to the carbon and nutrient cycling in boreal watersheds. Results here further suggest that boreal stream biofilm mineralization of DOM is regulated by watershed DOM source and composition. Labile carbon sources, such as algal inputs, may also play an important role in regulating DOM mineralization and the processing of nutrients by these biofilms. In nutrient-impacted streams, where primary production is high relative to nutrientpoor streams, biofilms may be stimulated to incorporate algal carbon sources. Yet in the boreal streams studied here, added labile carbon rarely enhanced the mineralization of extant stream DOM suggesting autotrophic-heterotrophic interactions represent a more important priming effect relative to changing DOM source in boreal streams.

Download or read book Wunderli Karl 1881 1961 written by and published by . This book was released on 1901 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeitungsausschnitte.

Download or read book Aquatic Organic Matter Fluorescence written by Paula G. Coble and published by Cambridge University Press. This book was released on 2014-07-14 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: A core text on principles, laboratory/field methodologies, and data interpretation for fluorescence applications in aquatic science, for advanced students and researchers.

Download or read book Relating Dissolved Organic Matter Composition and Photochemistry with High Resolution Mass Spectrometry written by Andrew Chapin Maizel and published by . This book was released on 2017 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: The irradiation of dissolved organic matter (DOM) produces reactive intermediates, such as excited triplet states of dissolved organic matter (3DOM), which contribute to the degradation of environmental contaminants. An understanding of how DOM composition determines the production of reactive intermediates is useful for predictions of contaminant fate and for relating the environmental processing of DOM to its photochemistry. To compare the reactivity of common 3DOM probe compounds, the photoreactivity of diverse, environmentally relevant waters was quantified with trans,trans-hexadienoic acid, 2,4,6-trimethylphenol, and furfuryl alcohol under ambient and standardized conditions. Measurements with each probe, including apparent quantum yields and pseudo-steady state concentrations, were found to exhibit unique sensitivities to variation in solution conditions. Comparisons of apparent quantum yields under standardized conditions suggest that the probe compounds each react with different 3DOM populations. 3DOM photoreactivity varies with molecular weight, but the underlying mechanisms are unclear. Therefore, the photochemistry and composition of ultrafiltration-fractionated fulvic acid isolates were compared with reactive intermediate probes compounds and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Terrestrially derived DOM was increasingly aromatic with molecular weight, while microbially derived DOM was invariant. 3DOM pseudo-steady state concentrations decreased with molecular weight due to increased 3DOM quenching, rather than variation in 3DOM formation rates. In order to relate DOM processing in natural systems to altered composition and photoreactivity, DOM from related lakes of different trophic status was evaluated with FT-ICR MS and reactive intermediate probe compounds. The presence of highly aromatic formulas, similar to lignin and tannin, correlated with 3DOM formation and light absorbance. Conversely, aliphatic formulas correlated with enhanced 3DOM quantum yields and environmental persistence. To investigate the unique composition and photochemistry of DOM from aquatic microbial sources, DOM from a wastewater treatment plant was evaluated by FT-ICR MS and UV-visible spectroscopy. Wastewater DOM contained molecular formulas that were compositionally similar to lipids, proteins, carbohydrates, and lignin, and were enriched in heteroatoms such as N, S, P, and Cl. Secondary treatment increased highly aromatic formulas and increased the number of identified heteroatom containing formulas, while other treatment stages produced smaller changes in DOM composition.

Download or read book Molecular Characterization of Dissolved Organic Matter by Ultrahigh resolution Mass Spectrometry written by Vanessa-Nina Roth and published by . This book was released on 2013 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Characterization of Dissolved Organic Matter DOM in Seawater written by Jasper Daniel Hendrik van Heemst and published by . This book was released on 2000 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spectroscopic Characterization of Dissolved Organic Matter written by John Robert Helms and published by . This book was released on 2012 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Photochemical and Microbial Degradation of Dissolved Organic Matter in the Lake Superior Watershed written by Megan J. Macdonald and published by . This book was released on 2012 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Dissolved Organic Matter and Determination of Its Biogeochemical Significance in Coastal and Inland Water Bodies written by M.S. Sankar and published by . This book was released on 2019 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a major component of natural waters and provides essential nutrients for aquatic organisms. However, excess DOM in the water results in water quality issues and affects the aquatic life negatively. The present research evaluated the source, composition, reactivity, dynamics, and the spatial distribution of DOM in diverse water bodies using spectrofluorometric methods in tandem with multivariate statistics. The study was conducted in the inland and coastal water bodies of Mississippi, Louisiana, and Alabama over a period of three years (2016 to 2018). Surface water samples were collected from spatially separated waterbodies with diverse land use and land cover classes. In addition, reactivity of DOM was assessed by conducting a series of laboratory experiments at varying magnitudes of sunlight and bacterial activity. Spatial distribution and mobility of DOM, nutrients and trace elements with respect to land cover classes and hydrology was evaluated using watershed delineation and multivariate statistics. Results suggest that microbial humic-like or protein-like DOM compositions derived from microbial/anthropogenic sources were less reactive than the terrestrial humic-like compositions originated from forests and woody wetlands. Furthermore, the sunlight was the major factor causing the degradation of DOM in the water bodies, while temperature had a minor effect. Additionally, the results also suggest that livestock fields in the pastoral and rangelands release a high amount of microbial humic-like DOM along with nutrients such as phosphates and nitrates into the water bodies. Present research identified the presence of four types of DOM in the study areas and were terrestrial humic-like, microbial humic-like, soil-derived humic-like and protein-like compositions. Additionally, trace element availability and mobility of coastal areas is influenced by local hydrology and precipitation. Research also identified forested areas as the major source of DOM to the water bodies of Mississippi. In conclusion, present research found that watershed land use and land cover, hydrology, and climate control the dynamics of DOM, other nutrients, and trace element delivery to the water bodies, while combined effects of light and bacteria are more efficient in reprocessing DOM chemistry within the waterbody.

Download or read book Anthropogenic and Environmental Drivers of the Input and Uptake of Dissolved Organic Matter in Temperate Streams written by Peng Shang and published by . This book was released on 2019 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dissolved organic matter (DOM) is a complex mixture of organic compounds and plays an essential role in regulating substrate and energy flows in aquatic ecosystems. However, environmental factors and biogeochemical mechanisms mediating the supply and uptake of DOM in streams are not well understood. The overarching goal of this dissertation is to assess the effects of the anthropogenic and natural drivers on the amount, source, composition, and fate of DOM in streams. The objective of Chapter II is to understand the effects of agricultural activities on DOM in a regional group of streams in Southeastern Alabama. The main finding is that agricultural land use increases DOC concentration and the proportions of terrestrial and microbial humic DOM compounds in streams, which suggests that agricultural activities accelerate the mobilization of organic matter from topsoils via enhancing oxidation, erosional transport, and shifting soil-to-stream flow paths. The objective of Chapter III is to identify the environmental drivers controlling the supply of terrestrial DOM in a Coastal Plain stream draining a forest-dominated watershed. The main finding is that discharge can be used to predict DOM supply across timescales, but other environmental drivers could be important at a given timescale. Specifically, the event-scale DOM supply is influenced by antecedent hydrological conditions and the duration of storms. At the diurnal scale, DOM variation is driven by physical dilution and concentration due to evapotranspiration. At the seasonal scale, DOM variation is mediated by organic matter availability from litterfall and discharge. The objective of Chapter IV is to determine the rates of natural DOM removal and identify the associated biogeochemical mechanisms in a second-order stream draining a forest-dominated watershed. The results provide the first record simultaneously measuring the uptake characters of humic-like and protein-like DOM, which demonstrates that humic-like DOM has a shorter uptake length and higher uptake velocity than protein-like DOM due to the preferential adsorption of humic-like compounds to benthic sediments. This dissertation improves our understandings of the supply and demand of DOM in subtropical streams in response to human land use and hydrological events, contributing to a greater understanding of the factors mediating the aquatic ecosystem response.

Download or read book CHARACTERIZATION AND TRANSFORMATION OF DISSOLVED ORGANIC MATTER DOM IN ENGINEERED ULTRAVIOLET UV PHOTOLYSIS AND UV BASED ADVANCED OXIDATION PROCESSES written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Dissolved organic matter (DOM) is a complex mixture of heterogeneous surrogate organic compounds and includes natural organic matter (NOM), dissolved organic nitrogen (DON), dissolved organic phosphorous (DOP) and soluble microbial products (SMP). DOM plays a key role in moderating the aquatic biogeochemical cycle in freshwater ecosystems. Shedding light into the composition of freshwater DOM will aid in understanding the biogeochemical dynamics of freshwater ecosystems and consequently the role of DOM as a local climate regulator. An increase in de facto wastewater reuse has made the removal of DOM present in wastewater imperative, as DOM can be potentially toxic to human health. Additionally, wastewater DOM can reduce the efficiency of the treatment performances of advanced treatment techniques such as UV-advanced oxidation processes (UV-AOPs), as DOM can screen UV light and scavenge reactive radical species, thereby reducing the concentrations of reactive radical species that are available to destroy the target trace organic contaminants. Therefore, understanding the molecular composition of DOM present in wastewater as well as in the effluent to surface water is crucial, as this knowledge will aid in upgrading treatment performances and subsequently contribute towards the effective removal of target contaminants. In this regard, ultrahigh resolution mass spectrometry was used to evaluate the molecular composition of DOM present in wastewater as well as in the effluent to surface water. DOM composition is characterized in terms of H/C and O/C elemental ratios and double bond equivalents (DBEs). Effluent DOM was found to comprise of a higher number of unsaturated aromatic species relative to wastewater DOM. Species with nitrogen and sulfur heteroatoms are less common among effluent DOM relative to wastewater DOM. In order to better understand the interference of DOM in the treatment performances of individual UV-AOPs, the transformation of a standard DOM isolate, i.e. Suwannee River Fulvic Acid (SRFA) as well as municipal effluent wastewater DOM (EfOM) were investigated in UV/H2O2, UV/free chlorine and UV/persulfate AOPs using ultrahigh resolution mass spectrometry. The changes in the H/C and O/C elemental ratios, DBEs, and the low-molecular-weight transformation product concentrations reveal that different DOM and EfOM transformation patterns are induced by each UV-AOP. DOM and EfOM transformation routes induced by hydroxyl, chlorine and sulfate radicals were mechanistically elucidated by comparing the known reactivities of each active radical species with specific organic compounds. In the UV/H2O2 system, distinct transformation of aliphatic components of DOM and transformation of olefinic as well as aliphatic components of EfOM was observed. In the UV/free chlorine system, transformation of aliphatic as well as olefinic species of DOM and transformation of aromatic species of EfOM was observed. Transformation of aromatic and olefinic moieties of both DOM as well as EfOM was observed in the UV/persulfate system. Transformation products of DOM such as chlorinated compounds are of concern due to their adverse health impacts. However, only a small portion of these compounds have been well-characterized, thus necessitating the characterization of the unknown compounds. Plausible structural information about chlorinated compounds produced from UV/free chlorine triggered transformation of DOM is provided through the means of tandem mass spectrometry (MS/MS) with ultrahigh resolution mass analysis. The two compounds of interest were hypothesized to be composed of alcohol, carboxylic acid and aldehyde/ketone groups.

Download or read book Natural Organic Matter in Water written by Mika Sillanpaa and published by Butterworth-Heinemann. This book was released on 2022-10-17 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural Organic Matter in Water: Characterization, Treatment Methods, and Climate Change Impact, Second Edition focuses on advanced filtration and treatment options, as well as processes for reducing disinfection by-products, making it an essential resource on the latest breakthroughs in the characterization, treatment and removal of natural organic matter (NOM) from drinking water. Based on the editor’s years of research and field experience, the book covers general parameters, isolation and concentration, fractionation, composition and structural analysis, and biological testing, along with removal methods such as inorganic coagulants, polyelectrolytes and composite coagulants. In addition, sections cover electrochemical and membranes removal methods such as electrocoagulation, electrochemical oxidation, microfiltration and ultrafiltration, nanofiltration, and membrane fouling. This book is a valuable guide for engineers and researchers looking to integrate methods, processes and technologies to achieve desired affects. Provides a summary of up-to-date information surrounding NOM Presents enhanced knowledge on treatment strategies for the removal of NOM Covers conventional as well as advanced NOM removal methods

Download or read book Aquatic Redox Chemistry written by Paul Tratnyek and published by OUP USA. This book was released on 2012-06-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides a comprehensive overview of aquatic redox chemistry through chapters contributed by many of the leading investigators in the field.